Don't mean to bust your bubble...but I would suggest to try the AirJet Chaffer that Mr.Gorden sells. I have used it in soybeans and corn...these are 2 of the heavier crops per bushel and I know wheat is also a heavy crop. The Airjet will get you a clean sample without any large amount of return. What you have to remember that the thrashing has to be completed first before you seperate the grain. My question is why would you want to use a hole type sieve. Feel free to ask questions. Thanks. JWK